Our long-range objective is to obtain a better understanding of the regulatory processes that control carbohydrate and fat metabolism during and after exercise and to determine how the long-term adaptions to exercise-training modify these regulatory processes. During this grant period we propose to spend a major portion of our research effort on the "insulin-like" effects of acute exercise and of exercise-training. We think that if it were better understood, the insulin-like effect of exercise could play a most important role in the prevention and treatment of adult onset diabetes. The proposed studies will be performed on isolated frog sartorius and rat epitrochlearis muscles, and in muscles in the perfused rat hindquarter preparation. One of our objectives is to further elucidate the mechanisms by which stimulation of muscle contraction increases the permeability of the muscle cell membrane to sugar. Our other objectives are: (a) to determine if a low "permissive" concentration of insulin is necessary for the acceleration of glucose transport by stimulation of muscle contraction: (b) to determine whether disposal of intracellular glucose can limit the rate of glucose uptake by muscle; (c) to evaluate the effects of perfusate flow rate on the rate of glucose uptake by the perfused rat hindquarter preparation: (d) to determine if fatty acids inhibit sugar transport across the skeletal muscle cell membrane; (e) to evaluate the effects of exercise-training on the permeability of muscle to glucose and on the insulin sensitivity of muscle; (f) to re-evaluate the mechanisms involved in regulating glycogenolysis during muscle contraction and glycogen synthesis following a bout of exercise.